Bill Thompson conceded the Democratic primary race on Monday, setting up a de Blasio-Joe Lhota showdown for all the mayoral marbles in November.

Thompson said at a news conference that he was proud to endorse de Blasio as the Democratic nominee.

“I am proud to stand here today and support Bill de Blasio to be the next mayor of the City of New York,” Thompson said. “Bill de Blasio and I want to move our city forward in the same direction. We share the fundamental same views and values — this is bigger than either one of us.”

”Thompson

De Blasio was standing behind Thompson. He said he had the honor to work with Thompson for many years and said there was “no man of greater integrity.”

“I am profoundly honored, I’m profoundly humbled to receive the support of Bill Thompson and his extraordinary coalition,” de Blasio said.

Gov. Andrew Cuomo played a role in brokering the deal, according to two people familiar with Thompson’s decision. Cuomo attended the City Hall event.

Cuomo, who was wearing a “Democratic’ blue tie like Thompson and de Blasio, completed the trifecta of party Kumbaya singing, even though GOP nominee Lhota was his man at the Metropolitan Transportation Authority. He said the city’s diversity is second to none.

”That diversity is the greatest source of strength that made us the greatest city on the planet and it’s going to make us an even greater city under the leadership of Mayor Bill de Blasio. It is my honor to support him,” the governor said.

”Thompson

In unofficial returns with 99 percent of precincts reporting, de Blasio had 40.3 percent of the vote — slightly more than the 40 percent threshold needed to win outright. Thompson was at 26.2 percent.

The Board of Elections completed the recanvass of machine votes in the mayoral Democratic primary election Sunday night. The elections board was beginning to count some 78,000 absentee and other paper ballots Monday.

A Board of Elections spokeswoman told WCBS 880’s Alex Silverman they should be finished tallying up the paper ballots by the end of the week.

“First the emergency ballots, then the BMD ballots with a manual count, and followed by the affidavit and absentee ballots,” Marricka Scott-McFadden, the Deputy Chief Clerk of the BOE’s Bronx office, told Silverman.

BOE Continues To Count Thousands Of Paper Ballots In Mayoral Race

Thompson criticized the city’s Board of Elections, calling the number of outstanding ballots yet to be counted “a disgrace.”

“Almost a week after the primary, we still don’t know the outcome of the election,” he said. “For all we know, given the Board of Elections, they may not finish counting the paper ballots until the runoff or until it’s over or until a few days before. Under those circumstances, it is impossible to even campaign let alone offer a meaningful choice to democratic voters.”

Thompson said as recently as Sunday he would wait until the official tally was finished.

“We’ll deal with things as they come about, but right now, we’re just waiting to see votes counted,” he had said. “I think that’s important. We want to see every vote counted.”

De Blasio said Sunday that he had no problem with Thompson waiting for the final tally.

“As I’ve said repeatedly, he has every right to call for a full count,” he said Sunday. “I respect that. I respect Bill. I’ve worked with him for many years.”

Thompson conceding, however, doesn’t necessarily mean he’ll avoid a runoff with de Blasio. If de Blasio’s final vote count ends up below 40 percent, the mayoral primary will be on the ballot on Oct. 1, because Thompson missed the Friday deadline to have it removed.

Thompson said Monday he will ask his supporters to vote for de Blasio.

“Today, I am proud to stand next to a great New Yorker and throw my full support behind him and I ask every single person who campaigned for me, supported me and voted for me to do the same,” he said.

Regardless of the mayor’s race, Democrats still will be asked to go to the polls Oct. 1. There’s a runoff between City Councilwoman Letitia James and state Sen. Daniel Squadron for the party’s nomination to succeed de Blasio as public advocate.

The general election is on Nov. 5. Adolfo Carrion Jr., a former Bronx borough president running as an independent, will also be on the ballot for mayor.

Once learning his main general election opponent had been determined, Republican mayoral nominee Lhota released a statement, saying: “I congratulate Bill on securing the nomination and look forward to a vigorous debate about the issues that matter to New Yorkers, like expanding our economy to create good paying jobs, keeping our streets safe and improving our schools. Over the next two months voters will see a stark contrast between myself and Mr. De Blasio.

“This election will be about moving New York City forward with the right kind of change. Dividing our city, increasing job-killing taxes and handcuffing our police is not the direction we need to take our city. I will be campaigning in every part of the city talking to all communities about my experience and vision for a government that works for the people of this city,” Lhota added.

Some feel Thompson’s about-face will give de Blasio the ammunition he needs to campaign on a platform to change the city and return it to the progressive values — the liberal values of the Barack Obama wing of the Democratic Party, CBS 2’s Marcia Kramer reported Monday.

“We don’t believe in allowing a tale of two cities as Democrats. It is our urgent, urgent imperative to create equality,” de Blasio said.

As the mayor’s race becomes a mano-a-mano contest with Lhota, pundits say this strategy is de Blasio’s path to City Hall.

“You know, I think he’s going to continue to make the case as we saw it today — a tale of two cities, something that Democrats are not going to accept,” Iona College’s Jeanne Zaino said. “I think we’re still going to need change from the current administration.”

Lhota has a two-fold task ahead of him. Experts say he has to reintroduce himself to voters because the Democratic primary took up so much of the political air these last few months, and it will also be an opportunity for him to play to Republican strengths like law and order and security.

“Joe Lhota is going to make the case that Bill de Blasio wants to return us back to the days of Dinkins. It’s going to make the city unsafe,” Zaino said. “I mean you could look at the shooting in Washington today. You know, people do have fears.”

Lhota wasted no time showing his own progressive side. He’s meeting Tuesday with the Rev. Al Sharpton.

The two will the hold a joint press conference, raising questions about whether Sharpton will remain neutral in the race or make an endorsement down the road.